1. Field of the Invention:
The orthotic of the present invention relates generally to appliances for inserting in a wearer's shoe to provide foot support and, more particularly, to a functional orthotic designed to help correction foot problems.
2. Description of the Prior Art:
Orthotic devices are typically divided into two main groups. The accommodative orthotic, such as an arch support, involves older technology which is considered a non-therapeutic appliance employed to minimize the intensity of the symptoms associated with various painful foot conditions. Typically, such devices may be constructed of relatively soft materials employing a cork or sponge filler sandwiched beneath a relatively thick top layer of leather or other material.
Functional orthotics are utilized to realign the foot in the wearer's shoe to assume a "neutral" or natural position. The level of therapy of a functional orthotic is directly proportional to the amount of control afforded to the supported foot. Such control stems from the effectiveness of the orthotic in holding or supporting the foot, and all its component parts, at specific angles for different phases of gait. The object of foot control is to restrict foot deviation from the desired angles and positions and, the more effectively such movement is restricted, the greater the reduction of foot pain.
It is understood in the art that control is primarily a function of the rigidity of the orthotic shell, surface texture and rearfoot and forefoot posting, combined with the dorsal and plantar shell contours. The prime consideration of health care professionals in prescribing a functional orthotic are the level of control, and adjustability of the contour to facilitate future changes in patient therapy needs. Of equal importance are the objectives of lessening foot pain and reduction of bulk to accommodate shoe fit and durability.
Due to the inherent limitations in the properties of materials and designs heretofore used in orthotic devices and methods of fabrication, a trade-off has been necessary between the desire to reduce bulk and maintain maximum control. Typically, in order to obtain the desired control and durability, the prior art frequently utilized a three to five millimeter acrylic thermoplastic shell. An orthotic of this type has been marketed which incorporates a shell constructed of a relatively uniform thickness of about three to five millimeters. It has been determined that this rather substantial thickness throughout the length of the orthotic is necessary to afford the necessary support and required durability. However, that thickness adds substantially to the bulkiness of the orthotic and elevates the foot in the shoe to such a degree as to limit usage often to only rather bulky and oversized shoes and detracts from the wearer's comfort. Contributing to the bulk is the fact that the forefoot edge is formed on its top, or dorsal, side with a relatively abrupt chamfer surface angling upwardly and rearwardly to form an included angle of about 30 degrees with the bottom surface. The bottom, or plantar, surface of that shell angles gradually forwardly and downwardly from the arch to the plane of such chamfer surface along a laterally extending line which contacts the top of the shoe inner sole. Consequently, the forefoot portion of that acrylic orthotic is typically elevated from the top surface of the shoe insole a distance of approximately five millimeters at the point where the chamfer abruptly tapers downwardly.
Prior art orthotics have been proposed in effort to overcome the disadvantages associated with bulkiness. One short orthotic endeavored to overcome the disadvantages of thicker heavy orthotics by proposing an orthotic which extends only along one side of the orthotic and wraps around the periphery of the heel terminating on the opposite side of the foot to define a shape somewhat in the form of a "question mark". A device of this type is shown in U.S. Pat. No. 4,360,027. Such devices, while affording some therapeutic advantages, suffer the shortcoming that the foot control afforded thereby is limited due to the fact that support is afforded for only one side of the foot and none for the forward aspect of the heel. Furthermore, such device suffers the shortcoming that the bottom surface thereof at the forward extremity extends substantially parallel with the top surface thereof and is not ground away at the extreme forward extremity to form a truly horizontal surface cooperating with the top surface thereof to provide a gradual and even transition from the orthotic to the supporting shoe surface. Furthermore, this device is not considered by those skilled in the art to be a functional device, but is rather an accommodative appliance, since its design is not of the single shell controlling rigid or semi-rigid type, but rather a flexible and therefore non-controlling laminated type. In fact, its construction is identical to many prior art accommodative appliances, except that the lateral area and central heel are cut out. The area chosen to be cut out further attests to the non-functional nature of this device, since the area located 1-4 cm forward from the center of the heel is considered by those skilled in the art to be an essential element of a functional device.
Prior art orthotics typically incorporate either intrinsic or extrinsic heel posting. An orthotic with intrinsic posting is formed by a shell material which is of constant thickness equal throughout the entire length of the device. The thickness of the post is thus limited by the thickness of the plastic shells from which such orthotics are typically constructed. For a thinner shell section in the heel area requiring heel posting, when the peripheries of the heel portion are turned upwardly to accommodate the contour of the heel, there is an insufficient thickness of material to leave a flat supporting surface extending the entire lateral and longitudinal distances under the heel, thus greatly detracting from the stability and effectiveness of the heel post.
Extrinsic posting is achieved by adding material to the bottom of the orthotic shell after the molding thereof has been completed. Extrinsic posting, while affording the advantages of allowing for a wider bottom bearing surface, suffers the shortcoming that the heel post must be formed separate from the shell, bonded thereto after forming of the shell is complete. In addition to being time consuming, such a technique frequently leaves an orthotic which is subject to damage and prone to heel post separation in use. It is also often contructed from materials which adhere fairly well but wear quickly. Furthermore, since extrinsic posts are constructed by the addition of extra material, they result in an increase in bulk. Consequently, there exists a need for an orthotic which achieves the advantages of both intrinsic and extrinsic posting and obviates the shortcomings of each. This is one of the problems to which the invention of the present invention overcomes. The present invention incorporates a heel post which is heat fused to the shell prior to forming to thus be formed therewith in a wholly unitized construction. This technique is referred to as integral posting.